A factor contributing to the rapid proliferation of smart phones and other mobile computing devices is the incorporation of sensors into these devices. Specifically, mobile computing devices can be equipped with many different types of sensors, including, but not limited to, a geolocation sensor (e.g. a global positioning system (GPS) sensor), a camera, a microphone, a velocity sensor, an accelerometer, a proximity sensor, combinations thereof, and so on. The incorporation of such sensors into mobile computing devices has contributed to a rise in a number of applications that perform a service based at least in part upon readings from such sensors. In an example, a mapping application can receive a current location of a user (from a geolocation sensor in a mobile computing device of the user that outputs location data) and can present the user with a map of a region immediately surrounding such user, as well as driving directions to different locations based upon the data from the geolocation sensor.
The mapping application described above only operates effectively, however, if the mobile computing device that includes the geolocation sensor is outdoors or proximate to a window, as conventional geolocation sensors rely upon receiving data from satellites to output location information. Therefore, if the mobile computing device is in an indoor environment and not proximate to a window, the geolocation sensor will be unable to output data that is indicative of the location of the mobile computing device. Location of a mobile telephone can be computed in an indoor environment by triangulating cellular network signals. Cellular towers typically output beacon signals, and a mobile computing device, at a given point in time, may receive beacon signals from multiple cellular towers. Based upon the signal strength of the beacon signals, the mobile computing device can estimate its location relative to the cellular towers. If the location of the cellular towers is known, the mobile computing device can estimate a global position of such mobile computing device.
The estimated position, however, of the mobile computing device is relatively inaccurate. For example, if the user of the mobile computing device is indoors at a particular address, the mobile computing device can determine that the mobile computing device is somewhat proximate to that address. For the purposes of an emergency response, however, the approximated location may be insufficiently accurate.